Four isolates of an unclassified microaerophilic bacterium resembling Campylobacter species were characterized by growth requirements, microscopic examination, biochemical characteristics, antimicrobial susceptibility tests, and protein profile analysis. The unclassified isolates were differentiated from Campylobacter jejuni, Campylobacter coli, Campylobacter fetus subsp. fetus, Campylobacter laridis, Campylobacter pylori, and an ovine isolate. The bacterium was fusiform shaped with a corrugated surface due to the presence of periplasmic fibers and had multiple bipolar flagella. Biochemically, the bacterium was separated from the Campylobacter controls by its negative catalase reaction, negative nitrate reduction, and no growth in 1% glycine. It was also resistant to ampicillin. Protein profile analysis demonstrated nine major protein bands present in the unclassified isolates that were absent in the Campylobacter controls. The bacterium also differed from the ovine isolate by its negative catalase reaction, rapid urea hydrolysis, and susceptibility to clindamycin, erythromycin, and tetracycline. Our results showed that the unclassified bacterium was distinct from the recognized Campylobacter species.

An unusual microaerophilic gram-negative bacterium was isolated from the stools of two individuals presenting with chronic diarrhea. This bacterium resembled Campylobacter species by colonial morphology and biochemical reactions. However, microscopic examination revealed a fusiform rod with a corrugated surface, rather than a spiral rod. This is the first reported isolation of this bacterium from humans. Since the first successful isolation of Campylobacter species utilizing selective plating media and optimal growth conditions (17), the number of clinical isolates has steadily increased (11). These human isolates include Campylobacter jejuni, which causes enteritis (21), whereas other Campylobacter species have been associated with diarrhea, enterocolitis, enteritis, and gastritis (6, 14, 16, 19, 20). This study is the first reported isolation of an unclassified bacterium from two humans with mild chronic gastroenteritis; this bacterium shares some cultural and biochemical characteristics with Campylobacter species. Case 1. A 47-year-old male with symptoms of gastroenteritis was seen in May 1985 by a physician in Madison, Wis. The patient had a history of recent travel to the Dominican Republic in January 1985 but appeared healthy until April, when he developed symptoms. He demonstrated a chronic diarrhea with two to three loose stools per day which were mushy but not bloody or watery. Other symptoms were fever, headache, and lower abdominal pain with no nausea or vomiting. Stool cultures yielded a gram-negative bacterium which resembled Campylobacter species on initial inspection. This isolate was subsequently lost during biochemical testing. A second specimen was requested, and the unusual bacterium was reisolated. Cultures for enteric pathogens, as well as microscopic examinations for ova and parasites, were negative. The patient was treated with erythromycin and became asymptomatic. Follow-up cultures were negative, and no relapse occurred. The family members of patient 1 were cultured for enteric pathogens, and a second isolate of the unusual bacterium was recovered from the 16-year-old daughter, who was asymptomatic. Other family members were negative. The bacterium was also isolated from an asymptomatic young dog (5-month-old female) owned by the family, but an older dog (16 years old) was negative. Case 2. A 40-year-old male with symptoms of chronic gastroenteritis was seen in October 1985 by a physician in Janesville, Wis. The patient had a 2-month history of six to eight soft-to-watery bowel movements a day. His stools were not bloody and did not contain mucus. He showed no weight loss or fever. No inflammatory changes were evident in the bowel by fiberoptic sigmoidoscopy. When stool cultures were performed for enteric pathogens, a bacterium resembling the bacterium in case 1 was isolated. No other

Brucella spp. are pathogenic intracellular Gram‐negative bacteria adapted to life within cells of several mammals, including humans. These bacteria are the causative agent of brucellosis, one of the zoonotic infections with the highest incidence in the world and for which a human vaccine is still unavailable. Current therapeutic treatments against brucellosis are based on the combination of two or more antibiotics for prolonged periods, which may lead to antibiotic resistance in the population. Riboflavin (vitamin B2) is biosynthesized by microorganisms and plants but mammals, including humans, must obtain it from dietary sources. Owing to the absence of the riboflavin biosynthetic enzymes in animals, this pathway is nowadays regarded as a rich resource of targets for the development of new antimicrobial agents. In this work, we describe a high‐throughput screening approach to identify inhibitors of the enzymatic activity of riboflavin synthase, the last enzyme in this pathway. We also provide evidence for their subsequent validation as potential drug candidates in an in vitro brucellosis infection model. From an initial set of 44 000 highly diverse low molecular weight compounds with drug‐like properties, we were able to identify ten molecules with 50% inhibitory concentrations in the low micromolar range. Further Brucella culture and intramacrophagic replication experiments showed that the most effective bactericidal compounds share a 2‐Phenylamidazo[2,1‐b][1,3]benzothiazole chemical scaffold. Altogether, these findings set up the basis for the subsequent lead optimization process and represent a promising advancement in the pursuit of novel and effective antimicrobial compounds against brucellosis.

Microfiltration has become a popular procedure for the concentration and enumeration of bacteria. We developed a rapid and sensitive method for the differentiation of gram-positive and gram-negative bacteria, utilizing a polycarbonate membrane filter, crystal violet, iodine, 95% ethanol, and 6% carbol fuchsin, that can be completed in 60 to 90 s. Gram reactions of 49 species belonging to 30 genera of bacteria were correctly determined by the filter-Gram stain. The sensitivities of the filter-Gram stain and conventional slide-Gram stain were compared by testing dilutions of Escherichia coli, Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenza suspensions in the presence and absence of whole human blood. The filter-Gram stain was approximately 100-fold more sensitive than the slide-Gram stain. The filter-Gram stain detected 2 to 100 bacteria, whereas the slide-Gram stain failed to detect less than 1,000 bacteria. The sensitivities of the methods were not significantly altered by the addition of whole human blood to the dilutions of bacteria tested. The filter-Gram stain could be a useful tool for the examination of body fluids with very low numbers of bacteria. * Corresponding author. MATERIALS AND METHODS Microorganisms. A total of 49 clinical and reference isolates belonging to 30 genera of aerobic, anaerobic, and facultatively anaerobic bacteria (Achromobacter sp., Acinetobacter calcoaceticus subsp. anitratus, Aeromonas hydo